Influence of leptin and the TNF system on insulin resistance in pregnancy and their effect on anthropometric parameters of newborns

Background. We studied the contribution of the tumor necrosis factor system and leptin to insulin resistance during the course of normal pregnancy. Methods. Forty‐five healthy pregnant women (15 in the 1st, 15 in the 2nd2 and 15 in the 3rd3 trimester) and 25 age‐matched healthy nonpregnant women as controls. Twenty‐three newborns delivered by women followed in the 2nd and 3rd trimesters were also investigated. Fasting serum immunoreactive tumor necrosis factor‐α, soluble tumor necrosis factor receptor‐1, soluble tumor necrosis factor receptor‐2, leptin (by enzyme‐linked immunoassay) and C‐peptide (by radioimmunoassay) concentrations in the patients and controls were measured. Body weight, length and head circumference of the newborns were analyzed in connection with the measured maternal parameters. Results. Significantly elevated tumor necrosis factor‐α, tumor necrosis factor receptor‐1 and ‐2, leptin, and C‐peptide levels were found in the 3rd3 trimester as compared with the 1st1 and 2nd2 trimesters and with the nonpregnant controls. Tumor necrosis factor‐α, tumor necrosis factor receptor‐2, C‐peptide, leptin concentrations and body mass index were found to be in a significant positive linear correlation with each other. Significant negative linear correlations were calculated among maternal serum C‐peptide, tumor necrosis factor‐α and leptin concentrations and the head circumference of the newborns. Conclusions. In conclusion, increased tumor necrosis factor‐α and leptin levels may contribute to insulin resistance in late pregnancy. Tumor necrosis factor‐α and leptin may be regulators of intrauterine bone development of newborns.